He was an opinionated op-ed man, a combative conservative on television, but through it all, Robert Novak prided himself on being a shoe-leather reporter.

That was true, in the sense that Novak regularly vacuumed up scraps and scoops from deep within the Republican Party. But his half-century career was also a monument to Washington insiderdom, to carrying coded messages for the sources he so assiduously courted.

Novak, who died yesterday at 78, was always well-wired on the right, and it was one such relationship, with George W. Bush's confidant Karl Rove, that drew him into a career-defining crisis.

"Karl and I had grown close since he began plotting Bush's path to the presidency as early as 1995," Novak wrote in "The Prince of Darkness," the memoir titled with the unflattering nickname he embraced. "I had never enjoyed such a good source inside the White House. Rove obviously thought I was useful for his purposes, too. Such symbiotic relationships, built on self-interest, are the rule in high-level Washington journalism."

Rove was a confirming source when the columnist identified Valerie Plame as a CIA operative in 2003, and Novak knew the resulting furor and federal investigation would permanently mar his reputation, which had always been marinated in controversy.

It wasn't hard to dope out Novak's favorite sources, even in the days when he wrote the syndicated column with the late Rowland Evans. Jack Kemp was a longtime favorite -- an "instant hero on the Republican banquet circuit by virtue of his tax cut gospel," they gushed in 1978. It was fitting that Novak went on CNN in 1996 to disclose that Bob Dole had picked Kemp as his vice presidential running mate -- an exclusive he got from Dole himself.

But Novak, who opposed the Iraq wars in both Bush administrations, did not always carry water for the GOP. "He was ideological but not partisan at all," says Fred Barnes, the Weekly Standard's executive editor. "I can think of a lot of columns he wrote pounding Republicans for being insufficiently conservative. . . . He really was the last of his kind, a columnist who did so much reporting. He always wanted to have one piece of information, little nuggets you hadn't seen anywhere else."

As Novak told me in 1997: "Maybe I'm working under roughly the same ideology as the people I'm writing about, but I'm not on their team."

Novak usually took my calls but was clipped and guarded in his responses. That was the case when I phoned him in September 2003 after the Justice Department began investigating the Plame leak, which was seen as retaliation by the Bush White House against recent criticism by her husband, former ambassador Joe Wilson. Novak said he was "surprised" at the uproar that his column, earlier that summer, had caused. "All the facts were out there for months and you didn't have this kind of firestorm," he said.

Even as some liberals denounced him as a traitor to his country, Novak largely refused to discuss the Plame affair, while revealing his sources -- Rove and former State Department official Richard Armitage -- to the special prosecutor in the case. Novak never expressed remorse, although he told me in 2006: "If I had it to do all over again, would I have done it? It's a hard question to answer."

I bumped into Novak occasionally at CNN, where I host a weekly media program. And though I'd like to report that he actually was a sweetheart -- "He's a lot nicer than he ever comes across on the screen," longtime sparring partner Jack Germond told me last year -- he often seemed to be scowling at someone.

Novak heightened his conservatism "by being a curmudgeon," says Margaret Carlson, a friend who tangled with him for years on CNN. "There was almost nothing you could embarrass him with. You'd say, 'Bob, do you want people in the gutters here like in Calcutta?' And he'd say, 'If they're not working, that's what happens in a capitalist society.' "

As Republican strategist Mike Murphy said yesterday on Twitter: "Novak loved his vampire-like public persona. Told me once, with a great laugh, that his one last dream was to play an assassin in a movie."

The onetime Associated Press reporter found his niche when he and Evans launched their column in 1963 for the New York Herald Tribune. Novak dined every other day at Sans Souci, chatting up sources over a bourbon or martini. The writing partners published a book on LBJ three years later that Arthur Schlesinger Jr. praised for its "objectivity." Novak later moved to the right, but stayed in the game even during Democratic administrations. In Bill Clinton's first term, Novak's top source was Dick Morris, an adviser who had mainly stayed in the shadows.

Novak's public persona was defined by his quarter-century at CNN, which he and Evans joined when the network was launched in 1980. In the pre-Fox era, Novak was the unsmiling face of conservatism on television. In his trademark three-piece suits, he sometimes snarled at guests on the left-right slugfest "Crossfire." In the late 1980s Novak defected from "The McLaughlin Group" and launched a second talk show, "Capital Gang," at CNN, where he and Evans also hosted a weekend interview program.

Although he would later be reviled for carrying water for the Bush White House, Novak found himself siding with the liberal opposition on Iraq. Days before U.S. bombs started dropping on Baghdad in 2003, Novak said on CNN that it was "a huge mistake" to go to war "against a country where you don't have the proof of the weapons of mass destruction. . . . This is preemption. And the preemption is a very dangerous, very dangerous doctrine indeed."

By 2005, after "Crossfire" and "Capital Gang" were canceled, Novak said in his memoir that he felt he was on his way out at CNN, where he was earning $625,000. He also could not appear on any day when the Plame case was in the news, because he was firmly in no-comment mode. Novak sealed his fate by getting into an argument with James Carville, saying an expletive on the air and stalking off the set. He later signed on as a Fox News commentator.

In one of his final columns in July 2008, the conservative columnist wrote that John McCain's presidential campaign was in "shambles." That same day, Bob Novak announced that he'd had a brain tumor diagnosed.